A wheel bearing apparatus that can support a vehicle wheel relative to a suspension apparatus and incorporates a wheel speed detecting apparatus to detect rotation speed of vehicle wheel to control the anti-lock braking system (ABS) is generally known. Such a bearing apparatus generally includes a wheel speed detecting apparatus with a magnetic encoder having magnetic poles alternately arranged along its circumference. It is integrated in a sealing apparatus arranged between the inner and outer members to contain rolling elements (balls) therebetween. A wheel speed detecting sensor detects the variation in the magnetic poles of the magnetic encoder according to the rotation of the wheel.
The wheel speed sensor is usually mounted on a knuckle after the wheel bearing apparatus is mounted on the knuckle to form a suspension apparatus. A wheel bearing apparatus incorporated with a wheel speed detecting apparatus where a wheel speed detecting sensor is incorporated in the wheel bearing in order to reduce the size of the wheel bearing apparatus as well as to eliminate troublesome air gap adjustment between the wheel speed sensor and the magnetic encoder has recently been proposed.
Japanese Laid-open Patent Publication No. 300289/2005 discloses one example of a wheel bearing apparatus incorporated with a wheel speed detecting apparatus. In this example, an encoder is fit onto an inner ring of the bearing. An annular sensor holder is mounted on one end of an outer member opposite to the encoder. A wheel speed sensor is integrally molded within the sensor holder and arranged opposite to the encoder, via a predetermined axial gap. The encoder includes an annular magnetic encoder. A seal is arranged at the inboard side of the encoder via the sensor holder. The seal has an annular first and second sealing plates mounted on the sensor holder and the inner ring arranged opposite toward each other.
In such a wheel bearing apparatus incorporated with a wheel speed detecting apparatus, a dedicated press-fitting tool is usually used to mount the sensor holder to the wheel bearing apparatus. More particularly, a metal annular fitting member forming the sensor holder is press fit onto the outer member using a press-fitting tool with a substantially “C-shape” configuration. A reason why the tool has a substantially “C-shape” configuration is to avoid pressing a weak holding portion of the synthetic resin that holds the sensor. Thus, a portion of the annular press-fitting tool is cut out to form the “C” shape.
However, sometimes a problem is caused by fact that the annular fitting member cannot be intimately contacted with an end face of the outer member. Thus, a constant air gap thickness or width between the encoder and the sensor cannot be stably obtained as well as the sealing performance becomes insufficient. This is because a sufficient pressing force cannot be directly applied onto the annular fitting member covered by the holding portion of synthetic resin when the annular fitting member is press fit by a press-fitting tool with a substantially “C” shaped configuration.